If you were contemplating on buying a ProMag product, just take the cash out of your wallet and flush it down the toilet. It'd do the same good but it'll save you the frustration dealing with a junk ass product.
In my quest to keep my scar as light as possible, I use a polymer mag while hunting. I have found that my scar is not mag sensitive like some other guns I have owned. The FN mags are far superior in quality but aftermarket mags seem to function.
I made the mistake of trying some ProMag magazines for the 9mm Walther P1 as well as several for the AR15. All were very consistent They consistently jammed all weapons they were used in. They were all failure to feed jams. I'll never buy another ProMag product again.